This thesis argues for a reformulated concept of nationality in order to avoid the problem of multiple national identities, which Lior Erez has shown to constitute a severe problem for the theory of liberal nationalism. At first, the problem’s plausibility is through idékritik, finding aspects of self-determination at its core. Thereafter, through a process of reflective equilibrium, the thesis concludes that the inclusion of Margaret Moore’s criterion of political aspiration, together with Ludvig Beckman’s all-affected principle, would avoid the problem. The thesis thereby highlights nationalism’s relationship to questions of self-determination, -rule, and sovereignty, a domain of nationalism that seems to be hitherto undertheorized.